A Time-traveler's Determination
by Reborn Crystal
Summary: Takes place two years Darkrai's defeat. It was supposed to a normal solo mission. Just check out strange activity in some ruins and report back any findings. Sadly for Autumn, a former human from a blackened future and Co-leader of Team Dreamstar, things are never simple or easy. (In which my PMD Explorers Hero takes the place of Frisk. Full Summary inside.)
1. Prologue: Forgotten Ruins

**Hey guys, it's the Reborn Crystal here. This is my first story, A Time-traveler's Determination. It's a PMD X Undertale crossover. Anyways, here's the full summary.**

 **Summary: Takes place two years Darkrai's defeat. It was supposed to a normal solo mission. Just check out strange activity in some ruins and report back any findings. Sadly for Autumn, a former human from a blackened future and Co-leader of Team Dreamstar, things are never simple or easy. Now in an unfamiliar world, she falls into a place known as 'The Underground', where monsters unlike Pokémon roam, seeking to take her soul. Autumn is determined to escape the Underground to see her best friend, Louis, once more. Will she befriend the monsters and escape? Will she perish trying? Or will she take a dark path and slaughter anything in her way to escape?**

 **I DON'T OWN POKEMON OR UNDERTALE. POKEMON IS OWNED BY NINTENDO AND UNDERTALE IS OWNED BY TOBY FOX.**

 **Enjoy~**

Prologue: Forgotten Ruins

Sunlight shined through the mouth of Sharpedo Bluff, hitting a certain human-turned-Ninetales' eyes. Her eyelids fluttered as she was aroused from sleep. Autumn groaned as she opened her eyes.

"Morning already?" she yawned, stretching her legs as she got out of her hay bed. She looked over to the bed next to her. "Better wake up, Louis."

In the bed next to her was a Luxray. This was her best friend, Louis. She couldn't believe that's it's only been three years since her and Louis met that fateful day on that beach and form their own exploration team, Team Dreamstar. It seem like so much longer. Then again, she guessed it was natural for her to feel that way. After all, she was an amnesic. Even though she knew that she was from a ruined future, Autumn still can't recall her life because that day she woke up on the beach.

"Hey Louis," Autumn said as she shook her friend awake. "It's morning. Time to get up."

Louis groaned as he slowly got up. "Five more minutes" he said, before slumping back down.

Autumn rolled her eyes. "Come on, Louis, it's time to get up. We gotta check out those check out those ruins today, remember?"

Recently, there had been some strange activity going on some ruins of an abandoned town called New Sun Town. A few months ago, some Pokémon who visited the ruin of the deserted town suddenly disappeared. Chief Magnezone and his Deputies Magnemites investigated and found no trace of the missing Pokémon or had any clue of what happened to them. The exploration teams that investigated turned up empty handed too. The case ran as cold as ice. However, about two weeks ago, it happened again, only this time it was an exploration team that went missing. Gold ranked Exploration Team Enigma had been one of the team investigating the disappearances. The team consisted of a Delphox, a Mismagius, and an Absol. They were last seen not so far from the ruins. Last week, Louis and Autumn decided to start investigating themselves.

Louis then slowly got up for real. His face seemed rather pale. "Yeah, you're right."

Autumn saw how pale he looked. "Woah, are you feeling alright, Louis?" she asked, the worry on her face what as plain as day.

"Truthfully, I don't feel so good," he admit groggily, "My stomach is tossing and turning. I feel like I'm going to throw up any second now."

"Maybe we should check out the ruins some other time," she said." You're obviously sick and in no condition to be outside, yet alone exploring."

"Just go without me," he mumbled. "We know that any information by investigating can help find those Pokémon. It's best not to let me being sick stop us from help them in any way we can. Besides, we've both been on solo missions before. It should be that hard."

She knew he was right. That every day wasted would decrease the chance of ever finding those missing Pokémon. She knew she's been on solo mission before, going to places like Oblivion Forest and Destiny Tower, and that Louis also been on his fair share on solo missions to places such as Treacherous Water and Zero Isle Center.

"Well, if you're sure," she said, still concerned over Louis, "I'll ask Aunt Kangaskhan if she can check on you later. You should go get some rest. I'll go and investigate the ruins."

Louis slumped back down to his bed of hay. "Okay" he murmured.

Autumn smiled as put the treasure bag around her neck and proceed to the entrance to leave.

"Autumn," Louis murmured.

"Yes," Autumn said as she turned around to face her best friend.

"Be careful out there, okay," he said.

Autumn flashed a teasing smile "And since when am I not?"

"I can think of a few times," he joked.

Autumn laughed. "Fair enough. Don't worry, I will. I'll see you later."

"See ya later, Autumn," he said as Autumn exited Sharpedo Bluff.

* * *

After getting the proper supplies and asking Kangaskhan to check on Louis later, Autumn proceeded head to the crossroads. She couldn't believe how peaceful it has been for the most part since Darkrai's defeat two years ago. During those two years, Team Dreamstar finally reached Guildmaster rank and her and Louis were finally able to evolve. Though she knew that here will always been Pokémon in need and outlaws causing havoc, crime has gotten down a lot and there were less chaos overall. In fact, this whole New Sun Town incident was the most chaotic thing that happened in the last two years.

When Autumn reached the crossroads, she pulled out her Wondermap from her bag.

"Let's see," She was trying to locate New Sun Town on her map. "From what I know about New Sun Town, it was an abandoned town east of the Northern Desert, soo… ah! Here we are."

She put the Wondermap away and proceed to head west.

* * *

New Sun Town was said to be once a small town that was establish so travelers heading to or from Northern Desert could rest. However, about 100 years ago, the residents of the town suddenly vanished without a trace and no one has lived there since. Some believe that the residents just abandoned the town one day due to the excessive heat and constant dust storms, while others believe that it was something much darker and sinister that caused their disappearance.

Autumn walked through the town, looking at the abandoned stone brick buildings that were worn by weathering and lack of care, trying to find any sort of clue to the recent disappearances.

She went inside one of the buildings. It seemed to be a house. The stone floor was completely covered in dust and bits of hay poking through the dirt. Not finding anything of importance, Autumn proceeded to the next room.

The next room appeared to be a study. Bit of old paper too worn to read scattered the dust covered floor. The remains of an old desk laid collapsed in the back of the room. At first glance, nothing seemed out of the ordinary, but as Autumn moved noticed that the dust surrounding the broken desk was displaced, some parts revealing the stone floor.

'Someone must have moved it recently' she thought. Autumn then pushed the remains of the desk out of the way. Beneath the remains was a trapdoor of sorts, possibly leading to a basement or cellar.

'Well, might as well check it out,' she thought as pulled open the door and proceeded to climb down the ladder that was placed there. At the ladder was a room with stone floor and walls and large circle painted onto the floor.

'What is this place?' she thought, 'Some ceremony place for a cult that uses Pokémon sacrifices for religious purposes? I hope not.'

On the eastern wall, she saw some very familiar ancient language.

'Unown? What's this going there?' she thought. After the Temporal Crisis and her return, Autumn took it upon herself to learn how to read the Unown language. She knew that the language hasn't really been used regularly in hundreds of years. She doubted that the previous occupants used the ancient language in their everyday life. She began to decipher it in her head and what she translated just confused her.

 _START LOAD SAVE RESET DETERMINATION._

"What?" she said out loud, "This doesn't make any sense!"

Shaking her head, she headed to check out the western wall, but what Autumn saw only made her even confused. On the wall were strange symbols. While she's didn't know how to decode footprint runes, she had seen Louis translate them, so she could tell that these weren't footprint runes. This code was unlike, to her memory, anything she had ever seen before. It consisted of different symbols such as snowflakes, human hand signs, flags, etc.

As she continued to stare at the strange code, trying to wrap her head around it, Autumn suddenly felt like someone was watching. She quickly turned around, only to find no one there. Most people who assume that it was just their imagination, but with everything she had been through, Autumn wasn't as easily fooled.

"Who's there?! Show yourself!" Autumn shouted as she walked to the center of the room. However, when she reached the center of the circle, it started glowing with black energy.

"Wha-"Autumn barely had time to register her shock as she suddenly felt herself falling.

The last thing Autumn knew before blacking out was a strange sensation running throughout her body.

* * *

 **Thanks for reading. Please fav, follow, and post your thoughts of this story so far in the review.**

 **Yes, in this story, Autumn (my PMD explorers hero) replaces Frisk.**

 **Anyways, this Reborn Crystal signing off.**


	2. Waking Up Again

**There's the second chapter of A Time-Traveler's Determination. Thank for those you read the first chapter and thank you for those who favored, followed, and/or review. I'll try to upload a chapter every Sunday.**

 **I DON'T OWN POKEMON OR UNDERTALE. POKEMON IS OWNED BY NINTENDO AND UNDERTALE IS OWNED BY TOBY FOX.**

 **~Enjoy**

* * *

Chapter 1: Waking Up Again

A throbbing pain in her head was the first thing that Autumn felt as she came to. The second thing was the fact that she was face down on the ground.

"Ugh, my head," she groaned as she got up and opened in her eyes. She saw that she was in a forest that she didn't recognize.

'What? How did I end up here?' she thought as she looked down. What she saw shocked her to her very core.

"What?! These aren't my paws!" Instead of yellow fur covered paws, Autumn was face-to-face with pale, naked, five-fingered hands.

"These are human hands!" She quickly got up. She saw that she now had long legs covered in dark blue jeans, that black combat boots covered her feet, and a dark gray shirt and olive green jacket covered her torso. She felt the long hair on top of her head and saw that it was dark brown.

"I'm h-human a-again," she stuttered, trying to figure out how this happened. "H-how is t-this p-possible? T-this doesn't make any s-sense."

Confused by this revelation, Autumn awkwardly started walking on her new legs. She decided to focus on why she was human again later. For now, she needed to find out where she was. As she was walking, she suddenly heard a noise in the bushes. Alert, Autumn was put on guard in case of an ambush. Suddenly, a small creature that Autumn thought looked similar to a Pachirisu. It was small, covered in chestnut colored fur and had a bushy tail.

'Never seen this Pokémon before,' When Autumn stepped forward and opened her mouth to ask the creature where they were, the creature ran off.

"Wait!" Autumn called after it, but it had already ran away. Deciding that it was pointless to chase after it, Autumn started to search the forest for any Pokémon she recognized. As she continued walking, she heard the sound of rushing water.

'A river,' she thought with relief, 'at least I won't die of dehydration.' She headed towards the sound. When she reached the clearing, she found the rushing waters of a river in front of her. She knelt down and cupped her hands to drink the water, but before she could take a drink, she heard a voice behind her.

"Don't move," the voice demanded. The voice was feminine and commanding. Autumn stopped all movement.

"Put your hands up where I can see them and turn around, slowly."

Autumn tried to try and reason with whoever this was. "Look, I don't know who you are, but why don't we calmly ta-"

"I SAID PUT YOUR HANDS UP AND TURN AROUND SLOWLY!" the voice shouted. Deciding that reasoning wouldn't do anything in this situation, she did what the voice told her to do. She put her hands in the air and slowly turned around.

She came face to face with a tall human woman pointing a stick at her. She had long blonde hair and ruby eyes. She was wearing a dark red robe and pinned to the robe was a familiar looking badge.

"That's an Explorer's Badge!" Autumn exclaimed.

The woman looked shocked by her exclamation, pulling Autumn up by her shirt and shouted. "Who are you?! How would you know that?!"

Autumn pulled away from her, reaching in her Treasure Bag for her own badge, and showed it to the woman. "Because I'm an explorer myself."

"Wait," she said, "Does this mean you're from our world?"

"Our world?" Autumn questioned, "What do you mean 'our world?"

"I guess you haven't realized it yet," she said.

"Realized what exactly?" Autumn asked, getting tired of going around in circles and not getting answers.

The woman sighed. "If you're from where I think you're from, I believe I should introduce myself first. I am Delphox, leader of the exploration team, Team Enigma."

Autumn's eyes went wide. "Wait, you're Delphox?! But Delphox is a Pokémon, not a-"

"Human?" Delphox finished her sentence for her. Autumn nodded. "Well, upon waking up in this forest, my teammates and I find that we weren't Pokémon anymore and we couldn't use our moves. We had somehow changed into humans. We quickly learned that this place is a completely different world from our own. However, since you know about Pokémon and are an explorer as well, that obviously means that you're from our world as well. Speaking of which, you never did answer my first question from earlier. Who are you?"

"Oh right," Autumn said. "My name is Autumn. I'm the Co-leader of Team Dreamstar."

"Wait, Dreamstar?" Delphox questioned, her eyes going wide. "as in THE Team Dreamstar, the ones who stopped the Temporal Crisis two and half years ago and the same ones who stopped Darkrai's wicked plans two years!?"

"Um, yes," Autumn said. She could tell where this was going.

"Oh wow, it's such an honor to meet such a well-respected explorer such as yourself," Delphox did a quick bow. "I sincerely apologized for my actions and behavior towards you earlier."

"It's fine, don't worry about, just please don't bow," Autumn said, feeling a lot of discomfort. "It makes me feel uncomfortable."

"Oh right, sorry," she apologized, "Anyways, how it did you end up here?

"Well, the last thing I remember was falling while I was in that creepy cellar with the Unown writing and that peculiar code with hand signs and other weird symbols," Autumn explained, "I was actually investigating those ruins to see if I could find any clues to your team's and the other Pokémon disappearances."

"The same exact thing happened to my team and the other Pokémon that went missing," Delphox said.

"Wait, you found them?!"

"Yeah, we managed to found the missing Pokémon, but there's one other issue," Delphox said. "We don't know how to get back to our world. We actually set up a camp not so far from here. Wanna come?"

"Well, I don't have anywhere else to go and I know nothing about this strange, unfamiliar world, so I don't see a reason not to," Autumn said, throwing her hands up into the air. "Lead the way."

As they walked to the camp, Autumn asked, "So is there a reason why you were so, um, aggressive back there?"

"My apologies, Autumn," Delphox said, "You see, a few days ago, some hooligans thought it would be funny to mess with our camp. Needless to say, when I saw you, I thought that they had returned and you were part of their group. That still doesn't excuse my rash actions though."

Autumn waved her off. "It's water under the bridge, no harm done. Let's just let bygones be bygones. You just didn't want a repeat of what happened before."

* * *

They continued walking until they reached another clearing. At the clearing were tents, a dining area, plants with berries that Autumn recognized, and a campfire pit. There were five people sitting around the table at the dining area, two girls and three guys. They seemed to be playing some kind of card game.

"Hey everyone, I'm back and I brought company," Delphox shouted. The people surrounding the table looked from their game.

"Who's this, Delphox?" one of the guys asked, eyeing Autumn suspiciously, "She's not an enemy, are they?" He was of average height for a human and had wild, midnight black hair and blood red eyes. He wore black pants and a white shirt with a black trench coat over it.

"Oh, light up, Absol," one of the girls said, "I'm sure Del wouldn't have lead her here if they wanted to cause us trouble." She was rather tall, even more so than Delphox, with the same color as Delphox and Absol and purple hair put up into pigtails. She wore a purple robe with a lighter purple lining and a necklace made out of rubies.

"Better cautious than have a repeat of the incident a couple days ago," Absol muttered, "or worse."

"Mismagius does bring up a good point though," one of the guy pointed out, "She can't be that bad." He had a tall, lanky stature with light red eyes and well-kept yellow-blond hair. He was dressed rather fashionably, donning green overcoat over a leaf green button up shirt and slacks with green fedora.

"That's enough," Delphox decided to step in, "Absol, I understand your concerns. Believe me when I say that I had the same suspicions toward too at first, but I can now say that she's not an enemy, but rather someone in the same situation we're in."

"Wait, do you mean that they're…" one of the girls said. She was rather petite and had long black hair and blue eyes. She wore a black and yellow sundress.

"Yep, she's from our world too," Delphox gestured to Autumn. "Why don't you introduce yourself?"

"Right," she said, "My name is Autumn."

The group looked surprised. "Autumn? Like THE Autumn of THE Team Dreamstar?" one of the guys said. He was of average height and had icy blue hair and light blue eyes. He wore a thick jacket that was zipped up and blue cargo pants. There were also blue some goggles of sorts on top of his head.

For the second time today, Autumn felt rather uncomfortable at all the attention. "Um, yes, but please, don't make a big deal out of it." The black hair guy stepped forwards towards Autumn.

"Um, I'm Absol, it's a pleasure to make your acquaintances," Absol held out his hand.

"Nice to meet you too, Absol," She shook his hand.

"I, uh, apologize for my behavior toward you earlier," he said, not looking her in the eye.

"It's fine," Autumn reassured, "So, is there anything I should know? Like camp rules or something?"

"Just make sure you do your fair share of work around here," Absol said, "I don't appreciate freeloaders."

"Oh relax, Absol" the purple haired girl came up put her arm around Absol's neck, "By the way, I'm Mismagius. The blond guy with the hat is Leavanny. The black haired girl is Helioptile and the guy that looks like he's dressed for winter is Cryogonal."

Autumn continued socializing with the other, getting to know them. The next couple of hours passed by rather quickly. Before she knew it, it was already dinner, which also passed by rather fast. After dinner, Leavanny helped her set up a tent for her. When they finished, she decided that it would be a good idea to retire for the night and went to sleep.

* * *

Over the course of the next week, Autumn had learned much about this new world. Like how instead of Pokémon, there were creatures called animals, and that a lot of human ate some kinds of animals. Or how humans in this world could talk to each from far away with devices called cell phones. She even learned that there was a human settlement nearby called Ebott City. Curious about this town, Autumn wanted to check it out herself. She even earned some money the humans in this world used by going some simple jobs, such as yard work, for the townsfolk. On the ninth day, Helioptile asked her a favor.

"Would you mind going to the library in town?" Helioptile asked nervously.

"Um, sure, but why you ask?" Autumn said.

"Well, you know, for research purpose," Helioptile said as twisted her hands nervously. " maybe one of the books there might have the answer to going home, uh, normally would ask one of Team Enigma to do something like this, but they're all busy today and the reason I don't go into town myself is, uuuhh…"

"You're scared of humans."

Helioptile looked at the ground sheepish. "It's not exact that I'm scared of them. It's just that I'm uncomfortable around them. I mean, I've heard stories about Team Sunshine and how one of their leaders was once human and about how you were a human that come from the future, but before coming to this world, I had never seen a real human being before, so seeing one in person in something outside of my comfort zone. I'm sorry if I offended you in any way."

"Helioptile, there's no need to be sorry," Autumn put her hand on Helioptile's shoulder, "Being uncomfortable in an unfamiliar place with things you've never seen before is perfectly normal. So Don't apologize for having a normal reaction."

"Thanks you."

"No problem and don't worry," Autumn smiled. "I'll do my best to collect as much research I can."

* * *

It was about ten in the morning when she got to the library. The library building itself was two stories tall with gray granite stone making up the exterior. The inside had many different sections, ranging from nonfiction to fantasy. Autumn saw that there was a section dedicated to something called 'anime and manga', though she had no clue what that was. She went over to the nonfiction section. Not knowing where to even start, she started picking random books off the shelves. After getting ten books, she sat down at the nearest table and started to read them.

The first book was on something called quantum physics. Most of the book just confused Autumn, though she get the theory of possible time travel and could help but smile mischievously at the thought of the scientists of this world's reaction to her not only being from another world completely, but also the fact that she's from a future where no time moves.

Deciding that she had enough of quantum physics, she move on to the other books. They ranged from topics such as cooking to engineering to someplace called Stonehenge. Not finding any of this particularly useful, she put the books back and got some more. She repeated this process of getting books, reading them, writing down anything that could be useful, and then put them back on the shelve three or four times. Before she knew it, it was already four in the afternoon.

"Four already?" She couldn't believe how much time had passed, "I better get going. Don't want to miss dinner."

While putting the books back, Autumn heard a whispering conservation between two people in the aisle next to the one she was in.

"You don't seriously believe that fairytale, do you?"

"Well, it would explain the rumors. After all, those who climbs Mt. Ebott are said never to return. It would explain where Hadrian disappeared to four years ago."

"Hadrian was an orphan. He probably ran away. We've both heard stories about that orphanage. I wouldn't blame him if he actually did ran away."

"But what if he went to Mt. Ebott? What if those-"

"We're done talking about this. It's just a myth. Come talk to me when you're done believing in fairytales."

There was then the sound of someone stomping away and the sound of footsteps following after them.

'Hmm, Mt. Ebott, anyone who goes there are said to never return,' Autumn pondered, 'Well, every legend at least has a gain of truth. I wonder…'

Autumn left the library and headed to the depot store with an idea forming in her head.

* * *

The next morning before dawn, Autumn woke up before. She started to make sure she had everything she needed. After that, she pulled out a piece of paper and pencil to write and note about where she was going and why. After finishing the letter, she left her tent. Autumn picked up a decent size stick that was laying on the ground, just in case she needed to defend herself. She then started to walk away from the camp.

"Going somewhere," Autumn stopped in her tracks and turned around, only to come face to face with Delphox once more.

Autumn sighed, knowing that she had been caught. "I want really hoping that no one would catch me sneaking out."

"Why is that and what's with the rope sticking out of your bag?" Delphox questioned, pointing to the small piece of rope that was poking out of Autumn's Treasure Bag.

"I was going to check out a possible lead that may or may not be a way home," Autumn confessed, not looking Delphox in the eye.

"Why did you tell us about this lead? We could have gone together."

"Because I don't want to get anyone's hopes up in case the lead is a dud," Autumn explained. "I don't know for sure if this lead is actually a way home. I'm going check it out myself."

Delphox sighed. "Can you at least tell me where this lead is?"

"Mt. Ebott," she replied, "Apparently, those who climb that mountain never return. Maybe the reason why no one returns is possibly because they're sent to a different world, like ours."

Delphox took a deep breath. "Look, I may not approve of you going by yourself, but you seem to determined to do this alone. Just be careful, okay."

"I will," Autumn said, "Just promise me something,"

"What is it?" Delphox said, having the feeling that not going to like this promise.

"If I'm not backing within the span of two weeks, don't come looking for me," Autumn said solemnly.

"What! How could you ask th-"

"Please, let me explain," Autumn said, putting her hands up, "If I'm not back within that time, it's likely that I'm dead. I don't want you or the others going on a wild Swanna chase just to find a dead body."

"But-"

"Delphox, please, promise me."

Delphox sighed. "Fine, I promise, but better not go dying on purpose."

"Wasn't planning to."

As Autumn turned to leave, she whispered thank you and proceeded to walk away from the camp and towards Mt. Ebott.

* * *

Mt. Ebott was an average sized mountain covered grass and trees. Though it wasn't as tall as some mountains such as Sky Peak, Autumn still did get tried from hiking up it. She decided to stop at a cave in the side of the mountain that wasn't so far the top. While catching her breath, she noticed that there was a gaping hole not so far the entrance of the cave.

Deciding that it may be a way back home, Autumn proceeded to tie one end of the rope to a column by the entrance of cave and throw the rest of the rope down into the hole. Autumn grabbed the rope and began to descend down into the hole.

As Autumn was climbing down, she suddenly heard the sound of something slowly ripping apart. She looked up and saw that the rope was starting to rip into two. Her eyes went wide.

"No! NO!" Autumn quickly tried to climb back up, but it was already too late.

*SNAP*

Once again, Autumn found herself falling down into darkness before blacking out.

* * *

 **And that's the end of the Introduction Arc. I plan to split up this story into arcs so it will be easy enough to follow, for myself and the reader. The next chapter is the star of the RUINS arc. I'll try to upload the next chapter next Sunday.**

 **For those who were wondering who Team Sunshine are, they're my version of the protagnist's rescue team from the first PMD games. I just wanted to make a reference to the first games.**

 **Hoped you enjoyed. Please Fav, Follow, and Review.**

 **This Reborn Crystal signing off.**


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